The present invention concerns a method for chemically separating gaseous mixtures of matter and particularly isotopes, using laser beams to make possible a directed chemical reaction of a mixture component, with a chemical reaction partner.
It is known that molecules which are composed of at least two different elements, absorb electromagnetic radiation in the infrared region. The infrared absorption spectra reflects the structure of the molecules, and are caused by the energy transitions of the rotation-vibrational states. As the vibration energy of a molecule depends greatly on the mass of the participating atoms, molecules which contain one kind of element with different isotopes, also have different spectra-scopically detectable absorption lines. This difference in infrared absorption can be used for isotope separation or more generally speaking, for the separation of matter, if the infrared emission line of a laser is brought into resonance with the rotation vibration line of the respective molecule of the kind of atom to be separated, so the molecule is excited thereby. The molecule excited in this manner can then be made to react from its higher energy level thus imparted, with suitable partners. In other words, the absorption of a light quantum by such a molecule constitutes a supply of energy which, with regard to the initiation of certain chemical reactions, has a similar effect as, for instance, an increase in temperature.
In the infrared region the energy which can be supplied by lasers at the present state of their technical development, is relatively small. However, the reaction can be promoted by adding to the chemical partner the additional molecular energy required, such as by the use of a laser beam of appropriate wave length or by heating the partner.
Thus, for the reaction UF.sub.6 + 2 HCl .fwdarw. UF.sub.4 + 2 HF + Cl.sub.2, a tunable Raman spin-flip laser (RSF laser) which is pumped with a CO laser can be used to excite the UF.sub.6. This laser is tuned to one of the absorption bands of the UF.sub.6 which lie between 5.2 and 6.4 .mu.m. The remaining energy required for the reaction partner HCl is added by exciting this molecule at 3.46 .mu.m by means, for instance, of a tunable laser.
In the above way the isotopes 238 UF.sub.6 and 235 UF.sub.6 can be separated from a gaseous mixture of the isotopes, the isotope combining with the chemical partner HCl, depending on which of the two is excited by the laser beam which, in turn, depends on the wave length of the beam used.
One way to carry out the reaction has been to enclose the gaseous mixture of isotopes and the gaseous partner together in a reaction chamber having a window at one end through which two laser beams of appropriate wave lengths are radiated so that they pass through the two components to cause their separate excitation as required for the directed reaction desired. When the additional energy required is added to the partner by heating, the partner may be heated outside of the chamber and then introduced to the chamber where the mixture of isotopes is being excited by the laser beam.
In connection with the foregoing, attention is called to the Schuster et al. U.S. Pat. Application Ser. No. 573,071, filed Apr. 30, 1975, where the practice of providing the addition energy required for the reaction, to the partner, is disclosed and claimed.